Hubble Takes Image of Impact Crater Tycho on Moon
Posted on May 4, 2012
NASA's Hubble Space Telescope recently took this image of the impact crater Tycho. The crater is one of the most violent-looking places on our Moon. The image reveals lunar features as small as roughly 560 feet (170 meters) across. The large impact crater (near the top of the image) was caused by an asteroid strike about 100 million years ago. The bright trails radiating from the crater were formed by material ejected from the impact area during the asteroid collision. Tycho is about 50 miles wide and is circled by a rim of material rising almost 3 miles above the crater floor. You can see a larger version of the image here.
Astronomers did not aim NASA's Hubble Space Telescope to study Tycho. The image was taken in preparation to observe the transit of Venus across the Sun's face on June 5-6. Hubble cannot look at the Sun directly, so astronomers plan to point the telescope at the Moon and use it as a mirror to capture reflected sunlight and isolate the small fraction of the light that passes through Venus's atmosphere.
The Hubble will observe the Moon for seven hours, before, during, and after the transit so the astronomers can compare the data. Astronomers need the long observation because they are looking for extremely faint spectral signatures. Only 1/100,000th of the sunlight will filter through Venus's atmosphere and be reflected off the Moon.
This is the last time this century sky watchers can view Venus passing in front of the Sun. The next transit won't happen until 2117. Venus transits occur in pairs, separated by eight years. The last event was witnessed in 2004. You can watch an animation of the upcoming Venus Transit here.